Elizabeth Bennet prides herself on her keen powers of observation. She has become very effective at the study of character of the individuals she meets and believes that her judgement is exceptional. Of course her judgement is very flawed, or else she would have easily been able to see through the lies that Mr. Wickham told her, not only about Darcy but about himself.
But in the following passages, Lizzie has a conversation with the older Charlotte Lucas, the subject is Jane's possible union with Charles Bingley. Elizabeth explains that Jane is not trying to trap him into marriage because he is rich, she is exploring the possibility of a potential love match with him and this takes time and consideration. Most particularly, she has to get to know his personality, his character.
Elizabeth asserts that Jane is not looking for a husband simply out of need of financial security, but she is looking for love. Obviously, Charlotte, who accepts Mr. Collins proposal without even knowing him, does not agree with this process. But Elizabeth is very confident that she and her sister have the right idea about finding a husband.
Elizabeth's pride is illustrated when she rejects Mr. Darcy's first proposal, it is a staggering refusal considering that she knows that her family home is in jeopardy of being taken by Mr. Collins, and that she, having already rejected Mr. Collins knows that marriage proposals don't come along every day, still sees no value in accepting the very rich Darcy's offer. Charlotte Lucas would not have thought twice about accepting him, her other sisters would have accepted, and probably even Jane.
Near the end of the book, Jane, believing that Charles is lost to her for good, accepts that the plan to have Charles fall in love with her did not work, and I think she would have accepted a proposal from another man because she is practical.
"Your plan is a good one,'' replied Elizabeth, "where nothing is in question but the desire of being well married; and if I were determined to get a rich husband, or any husband, I dare say I should adopt it. But these are not Jane's feelings; she is not acting by design. As yet, she cannot even be certain of the degree of her own regard, nor of its reasonableness. She has known him only a fortnight. She danced four dances with him at Meryton; she saw him one morning at his own house, and has since dined in company with him four times. This is not quite enough to make her understand his character.'' (Austen)
"Not as you represent it. Had she merely dined with him, she might only have discovered whether he had a good appetite; but you must remember that four evenings have been also spent together -- and four evenings may do a great deal.'' (Austen)